Wood filler composition



Patented 25, 1951 WOOD FILLER COMPOSITION Leo Boon, Southoid, N. Y., and William T. Smith,

Railway, N. .L, assignors to Interchemlcal Corporation, New York, N. Y., a corporation of Ohio No Drawing. Application August 19, 1948.

Serial No. 45.203

1 This invention which is a continuation in part of the application Serial No. 662,084, filed April 13, 1946, now abandoned, relates to the art of fill-' 8 pores of wood prior to the application thereto of suitable finishes.

Claims. (Cl. 260- 22) A The filler compositions which have long been used for this general purpose embody inert solid filler particles (which may be generally termed pigments) in an appropriate binder. These have generally been mixed in the form of a paste. To prepare the paste for use there is added thereto a suitable solvent for the binder and the entire composition and solvent is stirred to produce a creamy homogeneous filler in which the binder is completely dissolved in the solvent diluent. The mixture is then ready to be applied to the wood.

The resulting diluted filler is applied by brush or in any other convenient way to the surface of the wood to be filled, and after it has been allowed to stand for a while, during which time considerable diluent evaporates and the filler coating on the wood becomes dull in appearance, it 'is subjected to a padding" operation which consists in rubbing the thus deposited filler with a pad for the purpose of packing the filler into the pores of the wood, and removing the excess from the surface.

In prior fillers the pigments employed have generally been silicon dioxide, the function of which is to produce a mechanical interlocking with the wood structure, a suitable extender such as ypsum or kaolin to increase the bulk, and an appropriate porous material, such as magnesium silicate, which is well adapted as a bulky suspension aid for the other inerts.

In all prior fillers of the character described it has been the universal practice to employ as binder an oxidizing oil which is soluble in the solvent diluent subsequently added to the paste to prepare it for use. Linseed oil has been commonly used in this connection, as well as so-called long oil varnishes, so that when the padding or cleaning up operations of filling the wood are carried out, the filler composition would remain soft and workable for a'considerable period of time in order to permit the workmen to wipe 01f the excess deposited filler from the surface of the wood, leaving the top surface of the wood entirely clean but with the filler thoroughly deposited in the pores of the wood. I

It is obvious that filler compositions of this drying oil type require a lengthy drying P riod, depending upon the rate of oxidation and polymerization of the oil or the long oil varnish. Some attempts have been made to use quick drying binders in lieu of the drying oil or the long Oil varnish binder, but the setting of the filler deposited on the wood came soquickly and nonuniformly (the thinner deposits dried first and the thicker deposits dried later) thatit became impossible and impractical for a workman to clean reasonably large surfaces of wood; such as are found in-radio cabinets, furniture, etc., and to produce uniform results. This practice left streaks where the filler had dried and these streaks could not be removed unless the surfaces were again wetted with a solvent, in which case the filler was pulled out of the pores. On the other hand, if the work were to be cleaned without partial wetting, the pad ding" had to be done so quickly that very little of the filler composition was actually padded or packed into the pores of the wood. In addition, such quick drying binders require relatively high priced reducers or diluents, such as high boiling alcohols or esters, as against the more economical aliphatic hydrocarbons which are commonly used as thinners.

For these reasons it has been heretofore considered impractical to employ quick drying binders and the art has had to be content, all things considered, to continue the use of the relatively slow drying binders of the type to which we have referred.

The conventional fillers to which reference has been made, give a satisfactory end product insofar as the filling of the pores and the conditioning of the wood for a subsequent finish is concerned, but they all require a long time to dry, or to set to a point where, for instance, a lacquer coating can be applied to the wood. Usually overnight drying is best, but four hours has been considered the minimum period to condition prior fillers to take a lacquer finish. If lacquer or other similar coatings are applied over a filler which is not sufllciently dry or set, there is a marked tendency toward grayness of the pores and a shrinking of the fillerin the pores as it continues to set under the coating, causing blisters or pinholes in thecoating. For an occasional operation, the time required for the conventional filler may not be critical, butwhere large production is desired, the time of waiting for this type of filler to set results in a serious "bottleneck and materially slows down the production output. Furthermore, the binder of convential fillers, even if thoroughly dry, is easily attacked by the solvents of subsequent lacquer coatings and it is one of the detriments well known to the trade that such 7 fillers often pufi and swell under a lacquer coating, to shrink back finally to a point below the surface level.

The principal difllculty encountered in prior spasms attempts to use quick drying binders in wood filling compositions, was due to the fact that the binders were in colloidal solution in a solvent. Upon partial evaporation of the solvent, just at the time of padding, the fillerbecame sticky and unworkable.

In our co-pending application Serial No. 16,- 147, filed on March 20, 1948, we disclose a wood filler composition which sets in a fraction of the conventional drying time and yet permits the mechanical filling operation to be done easily and quickly without streaking of the surface of the wood or pulling the tiller out of the pores. The composition disclosed in the above identified application consists, in principle, of (a) a solvent soluble, quick drying binding material which substantially dries by evaporation of the solvent rather than by oxidation, (17) a solvent for the said binder, (c) pigments incorporated in the binder to produce a filler paste, and (d) an incompatible diluent which causes the binder to separate from the solution. Upon addition of the incompatible diluent a fiocculent precipitate occurs which adsorbs or rather envelops the pigment particles and forms agglomerates with them which remain suspended for some time after addition of so much of the incompatible diluent as is required to reduce the filler paste to working consistency. We found, after applying a filler of this composition to the wood and after permitting the vehicle to partly evaporate to the proper point 0 padding, that we were able to fill the pores of the wood with great ease and without stickiness or drag on the pad and without streaking or premature drying and that we could produce perfectly clear wood surfaces with the pores completely filled. Although the mechanical working ability of this filler is at least the equal of the slow drying oil types of fillers of the prior art, the new composition has the disadvantage that, after dilution to working consistency, the suspension settles soon upon standing. In addition, an accidental thinning slightlybeyond the proper working limit results in an irreversible breakdown of the flocculents, causing the binder and the pigments to collect at the bottom, a condition which cannot be restored through the addition of more of the paste.

Seeking to overcome the disadvantage of a suspension which at the required dilution is at the verge of collapse and which settles out upon standing, it occurred to us to replace part of the binder resin by another quick drying resinous material which, however, was soluble in the nonsolvent or in both, the non-solvent and the solvent for the first binder resin. In our experiments we used a 35% solution in xylol of a drying oil acid modified alkyd, conjointly polymerized with monomeric styrene, a type oi quick drying resin which is thrown out of solution upon the addition of mineral spirits, for instance. Thereto we added a 60% solution of a maleic anhydride modified ester gum, this resin being soluble in mineral spirits. The solutions were mixed at a ratio so as to supply the resins in approximately equal parts. However, when we employed the conventional pigment binder ratio of about 3:1 in making up the filler paste with these two resins as binder, we found that we were unable to produce a filler composition without detracting very seriously from the cleaning property of the material when applied to the wood. Only after raising the amount -of pigment substantially over the conventional 3:1 pigment-binder ratio of drying 011 type fillers and after increas ng the amount of thinner used from the customary 12 pound cut (12 lbs. of paste added to one gallon of thinner) to a 7.5 to 8 pound cut, were we able to produce a wood filler composition having the proper working consistency and the desired padding and cleaning properties.

At first we encountered difllculties, however, with a filler paste prepared by mixing the pigments into the xylol solution of the conjoint styrene-alkyd'polymer and then adding a solution of maleated ester gum in mineral spirits. Such a paste lacks package stability in that, after a short period of storage the solids tend to settle out and the solvent to accumulate on top. Upon dilution of the paste to working consistency a rather sharp separation is noticeable between the resin thrown out of solution and the continuous solvent phase and an early precipitation of the iiocculent resin. Similar results are obtained when the paste is prepared by mixing in the pigments last. However. if the order of mixing is reversed in such a manner that the pigments are wetted first with mineral spirits containing maleated ester gum in solution and the xylol solution of the conjoint styrene-alkyd polymer is then added. the composition remains not only package stable, but, after dilution to working consistency does not show any signs of separation. Moreover, the character of the suspension is greatly improved. The resin, thrown out of solution has no longer the flocculent appearance which we encountered before, but represents a gel-like coagulum which, in the presence of wood filler pigments envelops them and forms agglomcrates with them which remain permanently suspended, notwithstanding the high degree of dilution which we find necessary in order to provide the proper working consistency.

It is due to the gel-like coagulum in which part of the binder is present that the filler composition exhibits what may be termed a false body," as a result of which much more thinner is required than with previous filling composi-. tions to give a proper working consistency. We

' find that with some of our compositions we are thus able to save about one-third of the non volatiles as against customary wood fillers. Moreover, any accidental excessive thinning can readily be rectified by adding some more of the pas It is also due to the gel-like coagulum, coupled with the retention by the gel of liquid vehicle and soluble resin that the filler remains workable for a relatively longer time after the evaporation of excess vehicle and it is also this gel-like consistency which accounts for a surprisingly homogeneous filling of the pores of the wood. After the padding and cleaning, once the filler begins to set, the retained solvent evaporates quickly and the filler dries in approximately oneeighth of the time required for drying oil types of filler. When subsequent finishing coats are applied, the filler does not gray or bleed into the lacquer or varnish top coats.

By means of this principle we have been able to introduce extremely quick drying binders and to ameliorate to a great extent the difliculties and disadvantages which have been previously described.

For the filler composition of this invention we may embody the appropriate inert solid filler particles which have been heretofore employed, such as silicon dioxide, kaolin, clay, and magnesium silicate. In connection therewith we use as hinder the combination of two resins. one of which, in

- phthalates, or the conjoint polymerization products of a drying oil acid modified alkyd and styrene (of which the solvent-is xylol, for instance, and the non-solvent mineral spirits), and others.

As the other resin which is soluble in the nonsolvent for the first resin we have used with outstanding success a maleated ester gum, comprising about 12 per cent maleic anhydride, as well as hydrocarbon-polymers of the coumarone-lndene type, (such as "Cumar MEI-9 of Allied Chem. & Dye Corp., or Resin 3-17" produced -by The Neville 00.), having a melting point of 75-125 C. and made by treating solvent naptha or a coal-tar light oil fraction with sulfuric acid. In general, resins of the proper drying properties which are soluble in the non-solvent for the basic resin are suitable.

The diluent used in connection with binders of the character described must be one which is at least partially non-compatible with one of the binder resins and must be a solvent for the other. For this we have used mineral spirits or when app iedto thewood by brush or otherwise, the filler composition settles readily in the pores and, since it does not form a tenacious coating or layer, any excess thereof may easily be removed from the surface. After standing at room temperature for a period substantially the same as usual for conventional filler treatment. the filler composition will assume the mealy consistency and appearance of conventional fillers at that stage. By this time, theagglomerates may be packed firmly into the pores of the wood by a padding operation which cuts the filler level with the wood surface. Inasmuch as these fillers set or harden sufilciently to permit a subsequent ceating with lacquers and the like without difilculties in but a fraction'of the time required for the drying of the conventional dry- As it is desirable in the filling of wood for most finishes to have the pores of the wood high flash petroleum with highly satisfactory\ results. Other suitable diluents or combinations of diluents may also be used, such as a combination of mineral spirits, viz., aliphatic hydrocarbons, with an aromatic hydrocarbon. Hydrogenated and/or aromaticized aliphatic solvents may also be employed as the diluent. depending upon the resin employed, but they should be at least partially incompatible with one of the binder resins.

We also find that the filler composition improves still further upon the addition of small amounts, not more than 2 /2 per cent, of a plasticizer, such as dibutyl phthalate or triphenyl phosphate. They keep the pores well sealed upon drying of the binder and result in an improved adhesion of subsequent lacquer coatings.

The replacement of part of resinous binders by oleaginous substances, such as raw castor oil, diglycerides of soy oil fatty acids, or of linseed oil fatty acids, for instance, was found toaid materially in the efficiency of the cleaning operation without detracting perceptibly from the drying of the filler. It seems that during the padding these oleaginous constituents are squeezed out of the filler which is being packed into the pores of the wood. In collecting on the pad they act as nonadhesive lubricants and prevent, in this manner, any drag of the pad or pull out.

The mixture of the filler paste and the diluent should be of creamy consistency, having substantially the same appearance as prior conventional fillers when ready for use. This consistency may be obtained through the use of approximately one part by volume of paste to one and threequarter parts by volume of thinner, which, in the average, corresponds with one part by weight of thinner per 1.17 parts by weight of filler paste, or with a 7.7 pound cut (7.7 lbs. paste added to 1 gallon of reducer).

clearly visible, it is the practice to incorporate in fillers appropriate coloring matter. We accomplish this result byreplacing part of the filler pigments by appropriate earth pigments and bone black and the like. These serve, when the filler is used, to keep the pores quite dark, while the background color on the flake of the wood gives the desired color match. In

gilsonite we found an especially valuable material for this purpose.

It will be apparent from the foregoing that this invention is not restricted to specific ingredients. However, the following paste formulations are illustrative:

Example I Into 10.0 lbs. of mineral spirits there is thoroughly mixed:

Pounds A xylol solution containing 60% of 12% maleic anhydride modified ester gum--- 7.0 Silicon dioxide 37.0 Kaolin 13.0 Magnesium silicate 11.0 Dibutyl phthalate 1.75 Bone black 4.0 Burnt umber 1.75 Yellow lake pigment 0.75 An 82% solution of gilsonite in mineral spirits 1.75 A xylol solution containing 35 per cent of the conjoint polymerization product of 2.7 lbs. of a drying oil acid modified alkyd resin (38% phthalic anhydride, 22%

glycerol, 40% unsaturated oil fatty acids) and 1.5 lbs. of monomeric styrene;

the solution having a Gardner reading D 12.0

The order of mixing the constituents, as indicated in the foregoing and in the subsequent examples should be strictly followed. At least it is required, for attainment of the herein claimed results, to add the resin which is to be 76 resins and a non-solvent for the other portion.

The preferred ratio in most instances is one part by volume of the paste to 1.75 parts by volume 01 thinner.

Example II Into 10 lbs. oi mineral spirits there is thoroughly mixed:

Pounds A 50% solution of Neville R-17 resin, 9. coumaroneindene type resin having a melting point between 75 and 95 (2., dissolved in a 9:1 mixture of mineral spirits and xylol 5 Silicon dioxide 30 Kaolin Magnesium silicate 9 Diglyceride of soya oil 2 Dibutyl phthalate 2 An 82.% solution of gilsonite in mineral spirits 7 Van Dyck brown Yellow lake pigment 2 A xylol solution containing per cent of the conjoint polymerization product of Example I 8 Example III .Into 10.0 lbs. of mineral spirits there is thoroughly mixed:

Pounds A xylol solution containing 60% of 12% maleic anhydride modified ester gum--- 3.5 Silicon dioxide 36.0 Kaolin 13.0 Magnesium silicate 11.0 Diglyceride of soya oil -1 2.75 Dibutyl phthalate 1.5 Raw castor oil 1.5 An 82% solution of gilsonite in mineral spirits 1.75 Bone black 4.0 Burnt umber 1.75 Yellow lake pigment 0.75 A xylol solution containing 35 per cent of the conjoint polymerization product of Example I 12.5

Example IV Into 6.5 lbs. high flash petroleum there is thoroughly mixed:

' Pounds A xylol solution containing 60% of 12% Example V Into 5 lbs. hi-flash petroleum there is thoroughly mixed:

Pounds A mineral spirits solution containing 60% of 12% maleic anhydride modified ester gum 3 Silicon dioxide 30 Kaolin or clay 10 Magnesium silicate 10 82% solution or gilsonite in mineral spirits 8 Diglyceride of soya oil 5 Dibutyl phthalate 1 Raw castor oil 1 Van Dyek brown 15 Indian yellow lake 2 A 50% solids solution in xylol of an oil fatty acid modified glycerol phthalate (phthalic anhydride 46%, glycerol 28%, stearic and cocoanut oil fatty acids 13% each) 12 100 Example VI Into 5 lbs. of high flash petroleum there is thoroughly mixed:

' Pounds A xylol solution containing 60% of 12% maleic anhydride modified ester gum 3 Silicon dioxide 30 Kaolin 10 Magnesium silicate 10 An 82% solution of gilsonite in mineral spirits 6 Diglyceride of soya oil. 4 Dibutyl phthalate 1 Raw castor il 1 Van Dyck brown 15 Indian yellow lake 2 A 50% solids solution in xylol of the OH fatty acid modified glycerol phthalate of Example V '12 Example VII Into 10.0 lbs. 01' mineral spirits there is thoroughly mixed:

Pounds A 50% solution of Neville R-17 resin, a coumarone-indene type resin having a melting point between and 0., dissolved in a 9:1 mixture of mineral spirits and xylo1 5.0 Silicon dioxide 30.0 Kaolin 10.0 Magnesium silicate 10.0 An 82% solution 01' gilsonite in mineral spirits 6.0 Diglyceride of soya oil 5.0 Dibutyl phthalate 1.5 Raw castor oil 1.5

Van Dyck brown 13.0 Yellow lake pigment 2.0 A 60% toluol solution of a 1:1 tung oil modifled phenolic resin of the heat reactive type (resin BR-2175 of Bakelite Corp), corresponding to about 12 gal. oil length 6.0

The specific resin constituents of the foregoing examples are freely exchangeable or may be replaced by others having similar properties. Thus, the conjoint polymer of Example I which is thrown out of solution may be replaced by the modified glycerol phthalate of Example V, by

75 the modified phenolic resin 01' Example VII, or

by a natural resin such as gum accroides, while the soluble resin, represented by a modified ester gum in Example I, may be substituted by the coumarone-indene compound of Example 11, for instance, or, more generally, by any resin which has the proper drying properties and is soluble in the non-solvent for the first type of resin and in the thinner. Solvents or thinners, other than the herein disclosed may be employed, provided they answer the requirement of sumcient volatility and of being a solvent for one of the resins and a non-solvent for the other.

Quantitative changes of constituents of the herein exemplified compositions are permissible within a considerable range. We obtain useful filler pastes in accordance with this disclosure having from 10 to 18 parts binder. While 10 parts appears to be the practical minimum to obtain a proper sealing of the pores of the wood, the workability of .the filler is adversely affected if the paste contains more than about 18 parts binder.

The ratio between the resinous binder, which is present in form of the gel-like coagulum and the binder constituents which are in solution may range irom 2.5 to 7.5 arts of the precipitated binder per to 15 parts of binder in solution. The workability oi. the wood filler composi-- tion improves with substituting from one-fourth to three-fourths of the resin in solution by drying oleaginous substances.

The ratio of wood filler pigments including coloring pigments is preferably kept at 65-75 parts per 100 parts of paste. We prefer to add the non-coloring pigments in such proportions that about three-fifths to four-sixths is silicon dioxide while each kaolin and magnesium silicate is about one-sixth to one-fifth of them.

According to the foregoing examples the coloring matter added ranges from 6.5 to 1'7 parts per 100 but it is to be understood that we do not wish to limit our invention thereby. The use of more than 7 parts of gilsonite causes stickiness. At a ratio of 2 to 4 parts, gilsonite aids materially in darkening the pores, while 4 to 7 parts specifically tend to brighten the yellow undertone of the wood.

We claim:

1. A new wood filler composition, prepared by wetting 65 to 75 parts of wood filler pigments with the solution of a first resin comprising 5 to parts of maleic anhydride modified ester gum in 7 to 15 parts of a volatile hydrocarbon solvent of relatively low solvent power, and comingiing therewith a solution of 2.5 to 7.5 parts of a second resin in 2 to 8.5 parts of a volatile hydrocarbon solvent of relatively high solvent power; the said second resin being taken from the group consisting of alkyd resins, conjoint polymerization products of alkyds with mono meric styrene, and drying oil modified phenolformaldehyde resins.

2. The composition according to claim 1. in which one-fourth to three-fourths of the first resin is replaced by a drying oleaginous substance.

3. A composition according to claim 1, in which about 5 to 17 parts of the wood filler pigments are coloring pigments.

4. A composition according to claim 1, in which the noncoloring wood filler pigments consist to about three-fifths to four-sixths of silicon dioxide and to about one-sixth to one-fifth of each clay and magnesium silicate.

5. A new wood filler composition, prepared by wetting 37 parts silicon dioxide, 11.5 parts kaolin. and 11 parts magnesium silicate with 6.5 parts high flash petroleum, 3 parts of a solution in xylol of a 12% maleic anhydride modified ester gum, 1.75 parts of an 82% solution of gilsonite in mineral spirits, 2.5 parts diglycerlde of soya 011, 2.25 parts dibutyl phthalate, 2.25 parts raw castor oil, and co-mingling therewith 0.5 parts carbon black, 2.5 parts burnt umber, 7.75 parts Van Dyck brown, 1 part Indian yellow lake, 1.5 parts burnt sienna, and 9 parts of a 35% solution in xylol of the conjoint polymerization product v of 1.8 parts of a 40% drying oil acid .modified alkyd and 1 part monomeric styrene.

LEO ROON. WILLIAM T. sm'm.

REFERENCES orrEn The following references are of record in the file of this patent: 

1. A NEW WOOD FILLER COMPOSITION PREPARED BY WETTING 65 TO 75 PARTS OF WOOD FILLER PIGMENTS WITH THE SOLUTION OF A FIRST RESIN COMPRISING 5 TO 15 PARTS OF MALEIC ANHYDRIDE MODIFIED ESTER GUM IN 7 TO 15 PARTS OF A VOLATILE HYDROCARBON SOLVENT OF RELATIVELY LOW SOLVENT POWER, AND COMINGLING THEREWITH A SOLUTION OF 2.5 TO 7.5 PARTS OF A SECOND RESIN IN 2 TO 8.5 PARTS OF A VOLATILE HYDROCARBON SOLVENT OF RELATIVELY HIGH SOLVENT POWER; THE SAID SECOND RESIN BEING TAKEN FROM THE GROUP CONSISTING OF ALKYD RESINS, CONJOINT POLYMERIZATION PRODUCTS OF ALKYDS WITH MONOMERIC STYRENE, AND DRYING OIL MODIFIED PHENOLFORMALDEHYDE RESINS. 